This traffic impact assessment document discusses how a proposed development project will affect existing road traffic. It defines key traffic-related terms and outlines the standard process for conducting a traffic impact assessment. This involves collecting existing traffic data, conducting traffic surveys, analyzing current and projected traffic levels, estimating new traffic from the project, and determining if mitigation measures are needed to maintain adequate traffic flow. The assessment process helps identify impacts and inform planning to reduce congestion.

1. Traffic
Impact
Accessment
Traffic Impact Assessment or Traffic
Impact Analysis (TIA) is the effect of
the proposed project traffic on the
existing surrounding and road.
Presentation By
STUDENT | PLACK SOKHIT | M-TIE
Submitted to
DR | PHUN VENG KHEANG | DECEMBER | 23

2. STANDARD DEFINITIONS
Traffic impact accessment or Traffic Impact Analysis (TIA)
is the effect of the proposed project traffic on the existing surrounding and road.
Speed
Speed: The rate of motion or individual vehicles of a traffic stream. It is measured in meters
per second or kilometers per hour.
Volume
Volume: The number of vehicles at a given point on a road during a designated time
interval.
Time means Speed
Time means Speed: It is the mean speed of vehicles observed at a point on the road over a
period of time. 𝑉 =
𝑑
𝑡
Space mean speed
Space mean speed: It is the mean speed of vehicles in a traffic stream at any instant of time
over a certain length of the road. 𝑺𝑴𝑺 =
𝒅
𝒕
𝒏
Density
Density: It is the number of vehicles occupying in a unit length of a road at an instant of
time. The unit length is generally one kilometer
Capacity
Capacity: It is defined as the maximum hourly volume (vehicle per hour) at which vehicles
can reasonably be expected to traverse a point or uniform section of lane or roadways
during a given time period under prevailing roadways, traffic and control conditions.
Peak hour factor
Peak hour factor: It is defined as the traffic volume during peak hour expressed as a
percentage of average daily traffic. The peak hour volume in this case is taken as the highest
hourly volume based on actual traffic counts.
Presentation By
STUDENT | PLACK SOKHIT | M-TIE
Submitted to
DR | PHUN VENG KHEANG | DECEMBER | 23

3. IMPORTANT TERMS
Volume-Demand-to-Capacity Ratio (V/C):
It is a measure that reflects mobility and quality of travel
of a facility or a section of a facility. It compares roadway
demand (vehicle volumes) with roadway supply (carrying
capacity). For example, a V/C of 1.00 indicates the
roadway facility is operating at its capacity. It is a
common performance measure and is widely used in
transportation studies
PCU – Passenger Car Unit or ECS –
Equivalent Car Space:
It is the unit used for the conversion of different types of
vehicles on the road into a single unit for the ease of
calculation of the capacity of the road.
LoS – Level of Service
It is the measure of the current level of a particular
infrastructure and direct representation of the Volume to
Capacity Ratio, ranging from A to F.
Vehicle Type PCU/ECS
Factor
2 Wheeler 0.5
Car/Jeep/Taxi 1
Auto Rickshaw 1
LCV 1.5
Buses/2-Axle 3
Trucks-3 Axle 4
Trailer 5
Level of
Service
V/C Ratio
Description
2 Wheeler <0.3 Free Flow
Car/Jeep/Taxi
0.3 - 0.5
Reasonably Free
Flow
Auto Rickshaw 0.5 - 0.7 Stable Flow
LCV
0.7 - 0.9
Approaching
unstable Flow
Buses/2-Axle 1 Unstable Flow
Trucks-3 Axle >1 Forced Flow

4. What is TIA?
Traffic Impact Assessment
TIA is an important tool used to determine the transportation
and traffic impact of a proposed site development project
(upon full development) on the surrounding traffic and
transportation systems.Listen wie diese hier:
● It identifies the need for mitigation measures for a
transportation system to reduce congestion, as well as to
maintain or improve road safety.
● Local Authorities will use TIA as basic for assessing and
apportioning a developer’s contribution to road
improvements.
● Local Authorities also will use TIA to evaluate Traffic
Management Plan proposals.
● Provides necessary technical input to other relevant
reports such as Environmental Impact Assessment , Social
Impact Assessment, Development Plan ( Structure and
Local Plan), Transport Master Plan and the Road Safety
Audits.

5. WHY DO WE NEED TIA?
To offer
alternatives
Solution to traffic
improvement as well
as measures for the
road users.
To obtain the degree of control
At access requested by the
private/ government entities
To determine what type
of access required to be
considered and construction
To predetermine
future expansion
if its required 1
4
2
3

6. Level of Service (LOS)
LOS
60
B.NO DELAYS
No congestion
Reasonably free
flow,but speed depands
on Traffic flow
30
E.MINIMAL
DELAYS
Severe congestion
Very unstable flow,
possible short stoppages
70
A.NO DELAYS
No Congestion ,Free flow
with low traffic volumes
and high speeds
50
C.MINIMA
L DELAYS
Moderate congestion
Unstable flow;
Restricted drivers
chosen speed
30
F.SIGNIFICAT
DELAYS
Extreme congestion
Unacceptable
congestion ,stop-and-go
traffic; forced flow
40
D.MINIMAL
DELAYS
Moderate congestion
Unstable flow ; Restricted
drivers chosen speed
Level of Service
LOS provides an indication or measure
of the operational condition of the facility
concerned.
A range from “A” to “F” is
applicable, LOS “A” represents an
excellent level of operational
condition, while LOS “F” an
undesirable, exceedingly congested
and failed situation.
Reference: Road Traffic Volume Malaysia (RVTM) 2018

7. No Delays
<10 Delay per
vehicle(second)
Highest quality of service. Free traffic
flow with few restriction on
maneuverability or speed
LEVEL OF SERVICE (LOS) for Unsignalized Intersections
10-15 Delay per
vehicle(second)
Stable traffic flow. Speed becoming
slightly restricted. Low restricted
on maneuverability
15-25 Delay per
vehicle(second)
Stable traffic flow, but less
freedom to select speed,
change lanes or pass
25-35 Delay per
vehicle(second)
Traffic flow becoming unstable.
Speeds subject to sudden change.
Passing is difficult
35-50 Delay per
vehicle(second)
Unstable traffic flow.
Speeds change quickly and
maneuverability is low
>50 Delay per
vehicle(second)
Heavily congested traffic.
Demand exceeds capacity
and speeds vary greatly.
Very Short Delay
Minimal Delays
Minimal Delays
Significant Delays
Considerable
Delays

8. Delay per vehicle(second)
<10
Delay per vehicle(second)
11-20
Delay per vehicle(second)
21-35
Delay per vehicle(second)
36-55
Delay per vehicle(second)
56-80
Traffic Signal Condition
LOS
FACTOR
AFFECTING
LOS
OF
SIGNALIZED
INTERSECTIONS
Geometric Condition
Traffic Condition
 Signal Coordination
 Cycle Length
 Protected left turn
 Timing
 Pre-timed or Traffic
activated signal
 Ect.
 Signal Coordination
 Cycle Length
 Protected left turn
 Percent of truck
traffic
 Number of
pedestrian
 Etc..
Delay per vehicle(second)
>80
A
B
C
D
E
F

9. TRAFFIC IMPACT ASSESSMENT (TIA) PROCESS
FLOW
6
Collate existing data and
information
2 Architect/Town Planner
8
5
Discussion to determine
the scope, study area
and study methodology
1
Developer
3
Local Authority
7
Traffic Study
4 Appointment of a
Transport Engineer
9
Review the original layout
plan and propose any
improvement to the client
and land use.
Analyses:
 Trip generation
 Model split
 Trip distribution
 Trip assignment
 Analyses of LOS
 Problem to alleviate
or reduce the
identified probem

10. Part 1: Identification of site context and road
inventory
Site Name Distance from the proposed
project
● Nearest Arterial Road
● Nearest Sub Arterial
Road
● Nearest Railway Station
● Nearest Bus Station
 The hierarchy in terms of the network of roads is to ensure scale and efficient circulation of traffic. To achieve this,
through traffic routes are not be used for direct access to buildings or even to minor roads serving the buildings,
because in that case not only the capacity of the through routes will be reduced but the intersections will also be
unsafe.
 The principal factors considered in designation roads into appropriate classifications are the existing and proposed
land uses, overall travel demand, pattern of movement by various modes of transportation safety of traffic,
environmental considerations etc.
 The major Arterial, Sub-arterial and Collector Roads need to be identified in order to calculate the exact traffic
impact of the project.

11. Part 2: TRAFFIC SURVEY

12. Part 3: PEAK HOUR TRAFFIC, CAPACITY ANALYSIS AND FUTURE PROJECTION

13. Part 4: ESTIMATING PEAK HOUR TRAFFIC GENERATED BY PROPOSED PROJECT
Trip generation and forecasting
Four step model for demand assessment
 Trip generation models strive to predict the number of trips generated
by a zone. How many trips will be generated by a given location and
when will these trips happen?
 Trip distribution models strive to predict the number of trips that will
be made between a pair of zones for a particular trip purpose
What are the origins and destinations of these trips?
 Mode choice: the different modes available for a certain trip and what
factors affect the choice of a mode selection for a particular trip
Which mode of Transportation will be used to make the trip?
 Traffic assignment: Which route on the transportation network will be
used when making the trip?

14. Part 5: ADDING THE PROJECT GENERATED TRAFFIC TO TRAFFIC PROJECTION
 The Level of Service on the proposed road is going from D (Approaching Unstable Flow) to E (Unstable Flow).
 Therefore, the project is seen to have adverse effect on the surrounding area traffic and mitigation measures have to be put
in place for an efficient traffic management during and after the project construction.
CONCLUSIONS

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+855 97 7258 825 sokhit1@gmail.com
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